方法如何获取接口类型的输出参数？ [重复]

Given:

type Savable interface {}
type Customer struct {} // satisfies 'Savable'

func GetSaved(id string, s Savable) {
  // somehow get a reference to the object from cache
  s = cachedObject 
  // alternately, something like:
  // json.Unmarshal(jsonFromDisk, &s)
}

func Foo() {
  c := Customer{}
  GetSaved("bob", &c)
}

Trying a few configurations, I either get compilation errors related to "Expects *Savable, found *Customer", or the GetSaved function doesn't actually change what I want to be the 'output variable'. Is this doable, and I'm just not getting the right mix of interface/pointers/etc? Or is this not possible for some reason?

Edit: A working example illustrating the problem.

</div>

This works I converted it to bytes and Unmarshaled it back into your structure. Hope this helps. :) package main

import (
    "encoding/json"
    "fmt"
)

type Savable interface{}
type Customer struct {
    Name string
} // satisfies 'Savable'

func GetSaved(id string, s Savable) {
    // somehow get a reference to the object from cache
    cached := Customer{Name: "Bob"}
    byt, _ := json.Marshal(cached)

    _ = json.Unmarshal(byt, &s)

}

func main() {
    c := Customer{}
    GetSaved("bob", &c)
    fmt.Println(c)
}

Run link: https://play.golang.org/p/NrBRcRmXRVZ

You can use reflection to set the passed interface. Even when a struct reference is passed as interface, the underlying type info is not lost and we can use reflection.

package main

import (
    "fmt"
    "reflect"
)

type Savable interface {}

type Customer struct {
    Name string
} 

func GetSaved(id string, s Savable) {
    cached := Customer{ Name: id }
    c1 := reflect.ValueOf(cached)
    reflect.ValueOf(s).Elem().Set(c1)
}

func main() {
  c := Customer{}
  fmt.Printf("Before: %v
", c)
  GetSaved("bob", &c)
  fmt.Printf("After: %v
", c)
}

Here is the running link